docs: def handle_get_passphrase(self, conn, _):
          """Allow simple GPG symmetric encryption (using a passphrase)."""
          p1 = self.client.device.ui.get_passphrase('Symmetric encryption:')
          p2 = self.client.device.ui.get_passphrase('Re-enter encryption:')
          if p1 == p2:
              result = b'D ' + util.assuan_serialize(p1.encode('ascii'))
              keyring.sendline(conn, result, confidential=True)
          else:
              log.warning('Passphrase does not match!')